1. Найдите значение выражения: 1) 1/2 + 11/10; 2) 14/25 + 3/2; 3) 1/2 − 49/20; 4) 9/5 · 2/3; 5) 21/2 : 3/5; 6) 1 / (1/35 − 1/60).

1. \(\frac{1}{2}+\frac{11}{10}=\frac{5}{10}+\frac{11}{10}=\frac{16}{10}=\frac{8}{5}\).
2. \(\frac{14}{25}+\frac{3}{2}=\frac{28}{50}+\frac{75}{50}=\frac{103}{50}\).
3. \(\frac{1}{2}-\frac{49}{20}=\frac{10}{20}-\frac{49}{20}=-\frac{39}{20}\).
4. \(\frac{9}{5}\cdot\frac{2}{3}=\frac{18}{15}=\frac{6}{5}\).
5. \(\frac{21}{2}:\frac{3}{5}=\frac{21}{2}\cdot\frac{5}{3}=\frac{35}{2}\).
6. \(\frac{1}{\frac{1}{35}-\frac{1}{60}}=\frac{1}{\frac{60-35}{2100}}=\frac{2100}{25}=84\).

Ответ: 1) \(\frac{8}{5}\); 2) \(\frac{103}{50}\); 3) \(-\frac{39}{20}\); 4) \(\frac{6}{5}\); 5) \(\frac{35}{2}\); 6) \(84\).